1. Field of the Invention
The invention in the fields of biochemistry, organic chemistry and medicine relates to peptide compounds and methods of their use to treat diseases and conditions associated with movement, migration and adhesion of cells including diseases that involve angiogenesis such as tumor invasion and metastasis.
2. Description of the Background Art
Several disease processes have been demonstrated to require the invasion or migration of cells as part of their pathology. These include tumor invasion, tumor metastasis, pathological angiogenesis, inflammation, and endometriosis (Liotta et al., 1991; Fox et al., 1996; Osborn, 1990; Mareel et al., 1990; Aznavoorian et al., 1993; Lennarz and Strittmatter, 1991; Fernandez-Shaw et al., 1995).
In the case of tumor angiogenesis, quiescent endothelial cells can become motile in response to a variety of angiogenic growth factors as well as to changes in the basement membrane induced by tumor cells and various accessory cells found within a tumor (Blood and Zetter, 1990; Liotta et al., 1991; Odedra and Weiss, 1991). Neovascularization of a tumor enables the metastatic spread of aggressive tumor cells by (1) providing a route of escape for the metastatic cells as well as (2) nurturing the tumor by providing a growth-conducive environment (Cornelius et al., 1995; Blood and Zetter, 1990; Weaver et al., 1997; Weinstat-Saslow and Steeg, 1994; Leek et al, 1994).
The process of tumor metastasis may be viewed as bi-directional, comprising the following steps
(1) endothelial cells migrate into a tumor in response to a chemotactic gradient produced by the tumor cells or by accessory cells (stromal cells, leukocytes); and PA1 (2) aggressive tumor cells concomitantly invade toward the developing neovasculature. PA1 (a) at least about 20% of the biological activity of Ac-KPSSPPEE-Am in one or more of the following in vitro bioassays: (i) invasion in a Matrigel.RTM. assay; (ii) endothelial tube formation on Matrigel.RTM., or (iii) endothelial tube formation on a fibrin matrix in the presence of basic fibroblast growth factor and vascular endothelial growth factor; or PA1 (b) binding activity such that it competes with labeled Ac-KPSSPPEE-Am for binding to a cell or molecule which has a binding site for Ac-KPSSPPEE-Am. PA1 (a) SEQ ID NO:2 wherein the Glu at position 7 or 8 or both is replaced by one or any two of the substituent amino acids Gln, Asp or Asn; PA1 (b) SEQ ID NO:2 wherein Ser at position 3 or 4 or both is replaced by one or any two of the substituent amino acids Thr, Ala, Gly, hSer (homoserine) or Val.beta.OH (.beta.-hydroxyvaline); PA1 (c) SEQ ID NO:2 wherein the Lys at position 1 is replaced by His, Arg, Gln, Orn (ornithine), Cit (citrulline) or Hci (homocitrulline); PA1 (d) SEQ ID NO:2 wherein the Pro at position 2, 5 or 6 is replaced by Hyp (hydroxyproline); PA1 (e) an addition variant of SEQ ID NO:2, wherein Leu, Ile, Val, Nva (norvaline), Nle (norleucine), Met, Ala, or Gly is added to the C-terminal Glu or to any C-terminal substituent for Glu at position 8 as disclosed above. PA1 (f) an addition variant of SEQ ID NO:2, wherein any of the following peptides are added to the C-terminal Glu or to the C terminal substituent for Glu at position 8: Leu-(Gly).sub.n ; Ile-(Gly).sub.n ; Val-(Gly).sub.n ; Nva-(Gly).sub.n ; or Nle-(Gly).sub.n, wherein n=1-10. PA1 (g) an addition variant of SEQ ID NO:2 wherein one or more of the following residues or peptides is added to the N-terminal Lys, or to any N-terminal substituent of Lys at position 1 as disclosed: Gly, Lys-(Gly).sub.n ; Tyr-(Gly).sub.n ; or Gly-(Gly).sub.n, wherein n=1-10; and PA1 (h) a combination of one or more of (a)-(g).
The process of invasion may further fuel angiogenesis by the proteolytic release of growth/angiogenic factors bound to extracellular matrix (ECM), including basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and hepatocyte growth factor (HGF) as well as other factors including interleukin -8 (IL-8) and granulocyte-macrophage colony stimulating factor (GM-CSF). Also generated are proteolytic fragments of the ECM which are themselves chemotactic for both tumor cells and endothelial cells (Fox et al., 1996; Leek et al., 1994; Vlodavsky et al, 1990; Sweeney et al., 1991; Taipale and Keski-Oja, 1997).
It has been suggested that only 1-2% of the total cells in a tumor are capable of metastasis. As this statement is based on a static view of the tumor phenotype, it is probably inaccurate. In reality, metastasis appears to depend on disseminated tumor cells becoming exposed to an environment which supports their spread and survival (Weaver et al., 1997). In the majority of patients presenting with a clinically detectable primary tumor, metastasis has already occurred (Welch, 1997). Metastatic disease occurs when the disseminated foci of tumor cells seed a tissue which supports their growth and propagation, and this secondary spread of tumor cells is responsible for the morbidity and mortality associated with the majority of cancers. Clinical management of metastatic disease is often unsuccessful with conventional cytotoxic therapies. Metastasis differs substantially from the growth of the primary tumor in that it involves the simultaneous outgrowth of many foci which are phenotypically similar from the standpoint of their aggressiveness This outgrowth is dependent on the ability of cells that have metastasized to invade locally and to recruit neovessels.
By preventing interaction of adhesion molecules, the important process of cell migration/invasion and angiogenesis can be diminished or halted, with a number of important consequences for those diseases and conditions which are caused in part by undesirable cell migration, invasion and angiogenesis. In addition to vascular phenomena, such cell migration/invasion is important in tumor metastasis, which can be suppressed by the compositions and methods disclosed herein. Administration of effective amounts of these compositions will also disrupt the molecular interactions required for angiogenesis.
The art recognizes the need for novel treatments of subjects with cancer, in particular patients with metastatic cancer who have the poorest prognosis. Such treatment should be as devoid as possible of undesired side effects such as those associated with conventional chemotherapy and some of the experimental biotherapies. The present invention is directed to this objective. Inhibition of tumor cell invasion and endothelial cell migration (an important component of the angiogenic process) provide a novel approach to treating subjects with metastatic cancer. By inhibiting the local spread of tumor cells and angiogenesis at metastatic sites, metastatic foci should be induced to regress due to deprivation of their blood supply thus encouraging the subsequent expression of the cells' endogenous apoptotic program.
Furthermore, the inhibition of invasion of tissue by leukocytes and the concomitant angiogenesis would be useful for treating inflammation and other disease processes wherein cellular invasiveness is part of the pathogenic process. Inflammation and tumor invasion and metastasis and angiogenesis are known to involve similar mechanisms and extracellular factors (Liotta et al., 1991; Fox et al., 1996; Osborn, 1990; Mareel et al., 1990; Aznavoorian et al., 1993; Lennarz and Strittmatter, 1993).
Blasi et al. (U.S. Pat. No. 5,416,006) discloses plasminogen activators and their chemical modification, in particular phosphorylated uPA and tPA as thrombolytic agents. These workers examined phosphorylated uPA by generating tryptic phosphopeptides therefrom and noted the existence of KPSSPPEELK [SEQ ID NO: 1] (corresponding to positions 136-145 of uPA). This decapeptide was not tested for any function, nor ascribed any properties of functional relevance. More importantly, as disclosed herein, this peptide (unphosphorylated), capped or uncapped, is inactive in an in vitro assay of cell invasion.
Citation of the above documents is not intended as an admission that any of the foregoing is pertinent prior art. All statements as to the date or representation as to the contents of these documents is based on the information available to the applicant and does not constitute any admission as to the correctness of the dates or contents of these documents.